Study details: This prespecified secondary analysis of the SYNTAX II trial compared the results of noninvasive assessment of patients with triple-vessel CAD using FFR calculated from CT angiography with conventional angiography plus an invasive pressure wire.

Disclosures: The study was sponsored by the European Cardiovascular Research Institute with research grant support from Volcano and Boston Scientific. The presenter reported financial relationships with half a dozen medical device companies, but neither of those two.

That noninvasive method uses fractional flow reserve calculated from computed tomographic angiography, Carlos Collet, MD, said at the annual meeting of the European Association of Percutaneous Cardiovascular Interventions.

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Dr. Carlos Collet

Moreover, the fully noninvasive evaluation was considerably more informative than was conventional invasive angiography alone, which is the dominant diagnostic strategy utilized in contemporary clinical practice despite persuasive evidence of the added clinical value provided by invasive measurement of fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR). Indeed, the noninvasive approach evaluated in SYNTAX II reclassified 30% of patients from the high- and intermediate-risk tertiles based on invasive angiography to the low-risk tertile, a result with important implications for patient management because it renders them stronger candidates for PCI, observed Dr. Collet, a cardiologist at the Academic Medical Center of Amsterdam.

The results were hailed as a harbinger of a coming era in which interventional decision making will be based entirely upon noninvasively acquired anatomic and physiologic data. Conventional diagnostic angiography is predicted to fall by the wayside, with resultant savings in time and cost as well as avoidance of the risks of percutaneous diagnostic angiography, which entails considerably more radiation exposure than does noninvasive CT angiography (CTA).

“We are on the verge of a major change,” said Patrick W. Serruys, MD, PhD, professor of cardiology at Imperial College London, who was the senior coinvestigator in the study. “I think that the next disruptive moment in cardiology will be the introduction of the new generation of multislice CT scans replacing conventional cineangiography in the next 5-10 years. For the interventional cardiologist, to have the results of a multislice CT scan the day before a procedure is a wonderful bonus. You know in advance what you’re going to see, you can develop your treatment strategy, and you can spare contrast.”

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Dr. Patrick W. Serruys

This was a relatively small proof-of-concept study involving 77 patients with three-vessel CAD who underwent both CTA with noninvasive calculation of FFR and conventional invasive angiography with invasive physiologic assessment as part of the larger previously reported SYNTAX II (SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery II) study.

Compared with conventional invasive angiographic assessment with the use of an intracoronary pressure wire to measure iFR, the noninvasively calculated SYNTAX II score had 95% sensitivity and 61% specificity for detection of functionally significant stenosis, with a positive predictive value of 81% and a negative predictive value of 87%. And this was achieved using older scanners and software considerably less accurate than today’s rapidly evolving state of the art, Dr. Collet noted.